Did human social behavior evolve via group selection? E. O. Wilson defends that view in the NYT

Here’s one last (I hope) post on the brouhaha about the evolution of social behavior that I’ve covered over the last year or so.

I think E. O. Wilson must be feeling a bit beleaguered about the criticism he’s endured for his relentless advocacy of group selection. Not only was he an author of the Nowak et al. paper in Nature arguing that group selection rather than kin selection was the prime mover of social evolution in insects and humans—a paper that was excoriated by biologists who work on the evolution of behavior—but his new book, The Social Conquest of Earth, which makes the same group-selection argument, has also been strongly criticized.

Perhaps this explains why Wilson took to the pages of the Sunday New York Times to defend his views in an Opinionator piece called “Evolution and our inner conflict.” His thesis is this:

Within biology itself, the key to the mystery is the force that lifted pre-human social behavior to the human level. The leading candidate in my judgment is multilevel selection by which hereditary social behavior improves the competitive ability not of just individuals within groups but among groups as a whole.

“Multilevel selection” is another word for “group selection.”

How did social behavior evolve? Wilson gives a nod to kin selection, the idea that genes can evolve that produce behaviors favoring kin over oneself, so long as the genetic benefits of that behavior among all individuals outweigh the genetic costs to the altruist. (This is weighted by the degree of kinship between actors: behaviors favoring your brothers and sisters over nonrelatives will evolve more readily than those favoring cousins over nonrelatives.) But in the end Wilson dismisses kin selection in favor of selection among human groups:

This seems plausible, but in 2010 two mathematical biologists, Martin Nowak and Corina Tarnita, and I demonstrated that the mathematical foundations of the kin selection theory are unsound, and that examples from nature thought to support kin selection theory are better explained as products of multilevel selection.

Sadly, Nowak et al. demonstrated no such things. In fact, while they did offer what seems to be an alternative theory based on selection among groups, there is not a scintilla of evidence that it explains the evolution of social behavior in either humans or insects better than a kin-selection approach. Their model is in fact unable to rule out kin selection, since they begin with groups that are highly related and do not vary the level of kinship in their models to determine if, as they predict, kinship is not a “driver” of social evolution. So they simply cannot rule out kin selection as a powerful cause of social evolution.

Wilson goes on:

A strong reaction from supporters of kin selection not surprisingly ensued, and soon afterward more than 130 of them famously signed on to protest our replacement of kin selection by multilevel selection, and most emphatically the key role given to group selection. But at no time have our mathematical and empirical arguments been refuted or even seriously challenged. Since that protest, the number of supporters of the multilevel selection approach has grown, to the extent that a similarly long list of signatories could be obtained. But such exercises are futile: science is not advanced by polling. If it were, we would still be releasing phlogiston to burn logs and navigating the sky with geocentric maps.

Well, their mathematical arguments may hold, but others have shown that a). their model is basically one that does involve kin selection, and adds nothing new to the kin-selection perspective, and b). their empirical arguments about the intellectual vacuity of kin selection are serioiusly flawed. Several authors have produced lists of advances in our understanding of nature that have derived from a kin-selection perspective. In contrast, the idea of group selection has added virtually nothing to that understanding.

The number of signatories on the letters critiquing the paper of Nowak et al. is simply an indication of how much opposition their ideas faced in the scientific community. I urge readers with some biology expertise not to count the numbers, but actually read the critiques. No, science isn’t advanced by polling, but it is advanced by the open airing of arguments. All the numbers show is that a lot of scientists—virtually every prominent worker on the evolution of social behavior—have pointed out flaws of the group-selection approach.

For a clearly written critique of Nowak, Tarnita, and Wilson’s group-selection argument for social behavior, and a lucid defense of the value of kin selection, I highly recommend a recent paper by Andrew Bourke (reference below).

But on to the evidence that we humans became altruistic and cooperative by group selection. Wilson makes a strong claim here:

In fact, it seems clear that so deeply ingrained are the evolutionary products of group selected behaviors, so completely a part of the human condition, that we are prone to regard them as fixtures of nature, like air and water.

What are these supposedly group-selected behaviors? Wilson gives three (I quote):

“Among them is the intense, obsessive interest of people in other people, which begins in the first days of life as infants learn particular scents and sounds of the adults around them. Research psychologists have found that all normal humans are geniuses at reading the intentions of others, whereby they evaluate, gossip, proselytize, bond, cooperate and control. Each person, working his way back and forth through his social network, almost continuously reviews past experiences while imagining the consequences of future scenarios.”

Given that we’re social animals (see below), it is to an individual’s advantage to suss out one’s fellows in the group, and to your advantage to label potentially damaging or helpful individuals as such, for they can help or hurt not only you, but your relatives. There is no individual disadvantage that I can see to this behavior. Au contraire: any individual who can better read other people could have a reproductive advantage. So this can evolve via individual selection; there’s no need for group selection.

“A second diagnostic hereditary peculiarity of human behavior is the overpowering instinctual urge to belong to groups in the first place. To be kept in solitude is to be kept in pain, and put on the road to madness. A person’s membership in his group — his tribe — is a large part of his identity.”

Yes, but why does this suggest group selection? It’s a common mistake, one pointed out by Steve Pinker in his Edge essay, to mistake adaptations for living in groups with the notion of group selection. Cooperation can evolve by several forms of individual selection, including associating with others for protection or the ability to bring down larger prey, or through reciprocal altruism. The advantages of grouping are not only multifarious, but widespread in animals. And if you evolve grouping behavior, then you will likely evolve the urge to want to stay in a group. None of that needs group selection to evolve. Given the relative difficulty of group selection compared to individual selection, it would be extraordinary if the huge variety of animals who group all evolved that trait, and the penchant to aggregate, via group selection.

And finally, some xenophobia,which is probably the flip side of the second behavior given above:

“All things being equal (fortunately things are seldom equal, not exactly), people prefer to be with others who look like them, speak the same dialect, and hold the same beliefs An amplification of this evidently inborn predisposition leads with frightening ease to racism and religious bigotry.”

No problem for individual selection here: if you’ve evolved to be cooperative with others in groups, but simply haven’t encountered people who are different, it is to your advantage to be suspicious of them, for they haven’t passed the test of familiarity. Or, if groups compete with each other for food, individuals might also selected to be wary of those belonging to other groups. That involves group competition, but not group selection. A group-selection explanation would invoke xenophobia being maladaptive within groups, but a trait that has spread to all humans because xenophobic groups simply killed off the groups of “nice people.” That doesn’t sound so plausible to me.

In a book review by Michael Price of Brunel University, which I’ve discussed here, Price criticizes the view that human cooperation and other social traits must have evolved by group selection, pointing out the many features of human cooperation that suggest its evolution by selection among individuals. I won’t reprise the evidence here, but go to Price’s review (or my summary) and read the paragraph that begins as follows:

The view that group selection is needed to explain most human cooperation seems inconsistent with the fact that over the past several decades, most successful research on this cooperation has theorized that it is produced by individual-level adaptations (Price, 2011; Price and Johnson, 2011).

Price then enumerates the features of human “cooperation” that suggest it confers advantages to individuals. And if it does that, then there is no need to invoke selection among groups, which posits that “cooperative” traits are really disadvantageous for individuals within groups.

Probably at this point, during the habiline period, a conflict ensued between individual-level selection, with individuals competing with other individuals in the same group, versus group-level selection, with competition among groups. The latter force promoted altruism and cooperation among all the group members. It led to group-wide morality and a sense of conscience and honor. The competitor between the two forces can be succinctly expressed as follows: within groups selfish individuals beat altruistic individuals, but groups of altruists beat groups of selfish individuals. Or, risking oversimplification, individual selection promoted sin, while group selection promoted virtue.

“Probably”? We have no evidence that altruism and cooperation evolved in this way, and suggestive evidence it evolved by individual selection—and not only in humans. Sadly, Wilson, though at least expressing some uncertainty with the word “probably,” is severely misleading people about the evolution of cooperation. So are others, like Jon Haidt and D. S. Wilson. The force with which the adherents of group selection push their theory contrasts sharply with the paucity of evidence that their favorite process actually operates in nature. It’s puzzling. Well, maybe not so puzzling given that scientific egos and Templeton funding are on the line.

54 Comments

I don’t understand how Wilson, et al, can avoid the problem posed by presumed differences in altruism between groups in the first place. In order for a difference to exist it must have evolved differently within each of these groups. By regular old natural selection, kin selection, sexual selection, or drift. No? What value does group selection provide if it presupposes the others in the first place?

This is just a question of reductionism and the best level-of-description. Why describe human minds in terms of psychological states? In order for these states to exist they must be neural activity. Everything can be explained by regular old biochemistry, no?

The value psychology provides there is that explaining everything in terms of neurobiology (or if we want to be hardcore reductionists, physics) is intractable. I think the same argument can be applied to group-selection to counter your criticism.

Have I seen Wilson give a through and rigrous presentation of such an argument that group-selection is a good level-of-description in many cases? No, I have not, and I suspect he won’t make it. However, that doesn’t mean the argument can’t be made in general by a more pragmatic thinker.

I dont’ think that is correct. Kin selection (inclusive fitness) is perfectly capable of accounting for the development of altruism in social species. Group selection attempts to explain exactly the same thing but adds nothing of explanatory value.

Psychology does in fact add value to the understanding of (for example) humans behavior that is not provided (or even attempted) by neurobiology, at least not yet.

Altruism has to evolve within a population before it can possibly be selected between different groups (whatever exactly a group is). So accounting for it with this “higher order” process is explaining nothing, really.

JAC and RD both seem to define group selection as requiring “offspring” groups to bud off and compete with each other.

However, the Wilsons et al seem to define group selection in such a way that it includes groups getting bigger, possibly at the expense of other groups, without necessarily needing to produce new groups.

So, if a group containing a large number of altruists gets bigger while a group with fewer altruists gets smaller, JAC and RD would say that this is gene-level selection whereas EOW and DSW would say that this is group selection.

According to E. O. Wilson, altruism is detrimental to individuals within groups. There then arises the formidable problem of how you get groups containing large numbers of altruists to begin with, and why those aren’t unstable to the invasion of cheaters. Basically, you need groups to reproduce faster than individuals, which is why you need more than one group.

Which makes me think – how does he define human groups in the present day? And if we are all one big group, won’t the “selfish cheaters” infiltrate and spread throughout the population, thus reversing all the effects of group selection?

What if the groups that humans were competing with –back when individual adaptations for group cooperation were being refined by evolution — were other hominin species, and we got in an arms race with them for which species could get better organized (since, as Pinker said, war is more about organization, coercion, and false kinship signaling than altruism), and that led to evolved psychological adaptations for within-group cooperation?

That is, adaptations for cooperating to fight other hominin groups more effectively could have been built off of existing kin-selection and reciprocity driven adaptations for group cooperation. Then once those adaptations for cooperating to fight other hominins had evolved, they would turn out to be equally useful for fighting against other homo sapiens groups instead, after all the other hominins died out.

I realize that’s not group selection. But im not claiming it is. Im saying, couldn’t such an arms race plausibly have been a separate driver for the evolution of group cooperation, along with kin selection and reciprocity, that hasn’t been considered? Probably not, otherwise some expert would have brought it up already. But why not?

In order for a group to be selected, there has to be more than one group. This is a logical necessity for the very concept of group selection.

It leaves entirely unanswered the question of how any traits deemed beneficial to the group actually arise and reach majority within the group.

Honestly, I don’t think Wilson even knows what he means by “group selection”. Everything remotely valid he says reduces to nothing more than individual adaptation for group living, which is manifestly not group selection.

In technologically primitive human societies, large bands or villages fission. If such a group had a faster growth rate, it would fission oftener, that is, “reproduce” faster. If we’re hypothesizing gene complexes that lead to social behavior in humans, it is hard to see how this could not apply when bands fission. The more sociable members would be more likely to form the new groups.

Presumably the idea is that in some of the “new” groups, the relative disadvantage of non-altruistic cheaters would be overcome by the regular old inclusive fitness processes, presumably the same processes by which sociality gene complexes originally emerged. I don’t think Wilson has denied that there is such a thing as inclusive fitness. Any of the new groups that is genetically destabilized by excess numbers of non-altruistic cheaters grows more slowly, and fissions later. The ones that remain socio-genetically stable grow faster, and fission earlier.

I don’t know yet why Wilson thinks that this more rapid fissioning due to higher group growth rates is overall more important than inclusive fitness. That picture relates more closely to intuitive pictures of early human life than the inclusive fitness picture of species-wide evolution of social gene complexes, but early humanity is really too unknown to put much reliance on intuition.

One thing in Price’s (very good) paper struck me as odd, and I’m hoping someone here may be able to explain it to me. Twice, Price notes that altruism cannot evolve if relatedness is zero. (See, for instance, the conclusion section). But what about reciprocal altruism, as described by Trivers?

Thanks, Jerry, for clarifying that it’s not the mathematics but the failure to separate out the causal variable of kin selection that is the key to the criticism. The impressiveness of the math was the part that had me wondering if Nowak might be on to something, since previous math demonstrations that group selection cant in practice work seemed to me to make too many narrowing assumptions to definitively rule it out. I’d love to read the critiques themselves as you suggest but they all seem to be behind paywalls, so you’re doing us non-U types a great service here. Most of the non-paywalled critiques, such as Prof. Dawkins’s review, are (quite uncharacteristically in his case) frustratingly short on patient factual refutation and long on spluttering indignation and arguments from authority (however self-consciously made, they are still without any nourishment for the reader). Even Steven Pinker’s Edge post, lucid and much-needed as it was, didn’t make the problems with group selection as clear as you’re doing (of course, being an evolutionary biologist probably helps). Go, Jerry!

Steven Pinker’s essay was very clear, very thorough, and very devastating to the arguments for group selection. Any group selection proponent who reads this and does not feel embarassed, must be either dense or senile.

I do not have stong priors regarding group versus kin selection–afterall, both are group selection, it is just a matter of degree–but I was struck by the passages from the bible in another topic concerning the commandments from god to the israelites to exterminate the medinianites (or whatever, I can’t go back to check spelling or I’ll lose what I’ve written).

If this sort of thinking was widespread in our past, I can see how group selection might have operated for the human species.

Kin selection is not even a level of gene selection, so what are you talking about? You’re misunderstanding kin selection if you think it is differential survival of groups of relatives versus other groups of relatives. Don’t get confused by the names that irrelevantly mean “kin” is a type of “group”. The concepts of kin selection and group selection are wholly different. Kin selection is gene selection at work across bodies that carry copies of genes. Group selection is at best a useless metaphor, at worst a wrong theory supported by no evidence, and in the same category of error as Lamarckian evolution.

The many-authored Nature paper authors does not come out against group selection. It comes out against the criticism of kin selection. Queller’s comments on the recent Pinker article:

“Pinker is therefore correct that multilevel selection results can usually be seen as restating things we already knew in a different language. But I am loath to say that just because I speak English, others cannot speak in (as homage to Peter Kropotkin) Russian. ”

“None of this should be taken as an endorsement of E.O. Wilson’s recent flip-flop towards group selection, for two main reasons. First, Wilson makes the converse error that Pinker does – that if he describes a phenomenon in Russian, then the English account must be wrong. Second, Wilson’s Russian is itself rather garbled and the mathematical “support” from his collaborators is not group selection but pure population genetics that uses W.D. Hamilton’s neighbor-modulated selection (let’s call it Basque because it’s hard to learn). They in turn make the error that their laborious Basque invalidates simple English (but not, somehow, Russian).”

First of all, translating to a different language doesn’t change the meaning of the communication. This is no way analogous to what group selection is versus gene selection. EO Wilson is in fact using the same language (English, and biology jargon) but conveying a different meaning. That’s his whole point – he wants to say something different, not the same thing in a different way. Inexplicably, Queller sees analogy in two converse situations.

Second of all, Pinker never said anything in the article about restating things we already knew in a different language. He’s falsely attributing the analogy of languages to Pinker. What Pinker said was that group selection is sometimes “used as a way of redescribing the conventional gene-level theory of natural selection in different words”. Which changes the meaning. Pinker says, “To use the term in these senses is positively confusing, and writers would be better off referring to whichever phenomenon they have in mind”.

Languages are not that simple. Often you cannot simply translate word by word (idioms) and the meaning can only be conveyed approximately. For example, try telling a joke with a pun in it in a different language. It usually is not funny. Did you read Queller’s comment?

>>Languages are not that simple. Often you cannot simply translate word by word (idioms) and the meaning can only be conveyed approximately. For example, try telling a joke with a pun in it in a different language. It usually is not funny

Irrelevant to the point at issue. Doesn’t rescue the analogy to languages from being a bad analogy.

>>Did you read Queller’s comment?

Why would you even suspect that I did not? It’s a short comment. The link was convenient. He didn’t say a complicated hard to understand thing. He just made a poor analogy.

Because Pinker made the bad analogy. He starts with refuting groups as replicators when, AFAIK, nobody claimed that groups are replicators in the last 30 years. The debate has even long since passed the stage where DS Wilson would still claim that groups can be vehicles for replicators. If you must cling to this analogy, think of groups as providing either highways or off-road tracks for vehicles. Given the badness of this analogy, I guess you can see that Queller’s is better. It at least coveys an intuition about the much talked about mathematical equivalence.

As for dust having been thrown up since the Novak et al. (2010) paper, I don’t know what that kerfuffle is all about. They can’t in earnest try to reinstate groups as replicators!?

Which bad analogy did Pinker make? He did not make the analogy that groups are replicators. He simply showed that group selection would have been a valid explanation of group traits IF natural selection worked on groups (if groups really made copies of themselves, not if groups are replicators by analogy – that would be daft). But they don’t. He said: “But everyone agrees that this is not what happens in so-called ‘group selection.'” So group selection as an explanation for traits of groups adds nothing to ordinary cause and effect, or to “what we have always called ‘history.'”

Pinker started by examining “the idea that group selection is a viable explanation of the traits of human groups”. He tackled 3 ideas about group selection. He has to start somewhere.

Pinker showed that if group selection is not merely an analogy then it’s wrong. IF it is only an analogy, then it’s useless.

Given that Pinker did not make any analogies, then there’s nothing to rescue Queller’s bad analogy by comparison.

EOW strikes back!
Repeating the same thesis, that ‘group selection’ a new jargon that he invented, is a real deal (remind me of the late SJG’s punc-eq).

His defense on the theory is unclear, a lot of probablies, and most likely the theory will be discarded not long from now.

But his emphasis on what happened to human societies? the eusociality of man, I think is the real deal. He is not the first to discuss this, but he might be the one that raise it to general consciousness among serious scientists.

The explanation for the evolution of human groups such as family, clan, village, tribe, kingdom and empire – and the profound impacts of these evolutionary path on our psyche, our bodies even, are very important area of study.

I doubt that it will eventually be a ‘group selection’. The biggest issue with this EOW pet theory is, what is the replicator?

(EOW’s answer does not include any replicator so far, and that I think is unacceptable)

It’s hard for me to accept that a model of the evolution of social behavior in great apes can be adequate if it ignores individual learning, cultural evolution, and the Baldwin effect. If you accept that there’s been accelerated evolution of innate social propensities in humans, then I’ve just suggested an approach to accounting for it.

When modeling xenophobia (or more commonly its dual: ethnocentrism or contingent-altruism) one usually uses a game theoretic paradigm, where interactions are single rounds of prisoner’s dilemma. In such a setting cooperation is clearly detrimental to you in the sense that it opens you up to exploitation by defectors. If you model this with the replicator equation that you get the obvious result, selfish agents (ones that defect both from in-group and out-group) dominate. The modeling question than becomes under what conditions can you reverse this to get ethnocentric behavior (in-group cooperation, out-group defection).

It becomes much more attractive as an explanation. However, it is often possible to come up with very convoluted kin-selection explanation of this (look at some of the other work of P.D. Taylor for some complicated examples), but these are much less elegant than the group-selection accounts. One should really think of the distinction between kin-selection and group-selection as analogous to the difference between particle-physics and statistical mechanics. For some models one provides a better fit, and for others the other. However, for all models the more ‘basic’ (i.e. more reductionist approach) can be given, but often it is too convoluted and not enlightening.

Your model and the other two models don’t show support for group selection at all. I don’t see how group selection “becomes much more attractive as an explanation” in any of these models. You were not modelling competing and differential survival of groups, nor altruism. Your model shows only how certain cooperation strategies can evolve given the individual ability to discriminate. You’re basically modelling the evolution of what Daniel Dennett calls “groupishness adaptations”, you’re not modelling group selection.

The models are not there to show support for group-selection. For me group selection is just another level of description, so even the concept of ‘showing support’ for a level of descriptions doesn’t make much sense. I agree that in my model it is not a very useful description. However, Antal et al. basically relies on group selection and escaping tags that have high numbers of defectors by mutation. It is very convenient to think about those sort of models in terms of group-selection. Similarly with that groups new paper:

It puzzles me that the ‘group selection’ versus ‘kin selection’ debate has not been resolved. Perhaps Elliott Sober (a very distinguished supporter of group selection) could be persuaded to comment on why this is so. In the meantime, here is an apt quotation from Robin Dunbar on the distinction between group selection and multilevel selection.
“In multilevel selection again, the unit of evolutionary cost-accounting is the gene, and not the group. Group-level processes are intended to facilitate the successful replication of the individual member’s genes, not to facilitate the successful replication of the group. The distinction is subtle, but crucial” (Dunbar 2008)

I take it the majority of people posting on this site agree that group selection is a non-entity. I’m hoping for some help with a debate I’m currently having with someone who is a little more adept with biology knowledge. My case is that group selection doesn’t work because it doesn’t focus on the replicator – the gene. His argument seems to be that at the cell level, the lines between “replicator” and “vehicle” are blurred, and that vehicles are replicators in their own right.

Unfortunately my knowledge is not sufficient to understand some of what he’s saying, and he doesn’t seem to be able to simplify it for me. I’m looking for someone to a) explain what he means by the following statement and b) show me why it’s right or wrong. Please note, I’m not looking for a debate right here right now, only info on specific material from a debate occurring elsewhere. All knowledge is useful though I guess.

Here is the exact section of his post that I don’t understand:

“But other things were going on. Cell membranes were [or some functional equivalent] were “required” by these protogenes to allow sufficient concentration, and provide some shelter from environmental perturbations. Amino-acids began to be associated with particular bases, until we have our three codon per amino-acid system today. Once that became possible, then peptides, and eventually proteins could take on a structural or metaboloic role.

The cell membrane presents no great problems, because it does not need to be encoded because bilipid layers can form into membrane spontaneously, and peptides and proteins added much later to give signalling and adhesion properties became incorporated in the protocell genome.

But already, at the level of the cell, there is a naunced difference between the NS of chemicals [ribozymes] and the protocells. The whole is more than the sum of its parts because we no longer have the genes being directly selected, but the vehicles [the cells]. ”

Cells replicate, but only during the life of a single body. Gene replication takes place over much longer periods of time. Evolution is changes in gene frequency in populations over time. The fact that genes are selected on the basis of phenotypic (cellular, or whole critter level) doesn’t change these basic facts.

[…] counter-blasts from inclusive fitness theorists such as Richard Dawkins, Steven Pinker and Jerry Coyne. Now, perhaps all unbeknownst to themselves, the group selectionists have played the “virtue” […]